The present invention relates to improvements in toasters, particularly those toasters with one or more upwardly open slots to receive a product such as a slice of bread, a crumpet, a muffin or the like to be toasted.
Although not very common, fires can occur when toasters are utilized. The cause of such fires include (1) a build up of crumb material in the toaster base; and (2) a food product being toasted for a period of time that exceeds the normal level for that product due to operator misuse or a malfunction in the toaster itself.
In U.S. patent application Ser. No. 08/146,251 filed Nov. 1, 1993 and assigned to the same assignee as the assignee hereof there is disclosed a toaster of the kind in which one or more upwardly open slots are provided to receive a product to be toasted. In this patent application there is also disclosed a single pivotal (flameproof) flap or two such flaps adapted to close or open the upper access slot or slots of the toaster. While these arrangements are satisfactory from the point of view of containment of a possible fire within the toaster, they do have a practical disadvantage, particularly when relatively narrow body single slot toasters are used. The heat within a toaster body is created by toasting or heating elements and the toasting effect is primarily generated by radiant heat from these elements. The elements also, however, create convection heat most of which normally escapes through the upper open access slot during operation of conventional toasters of this design. If, however, a cover flap closes the upper access slot during a toasting cycle most of the convection heat is retained within the toasting compartment thereby significantly affecting toasting performance and possibly harming toaster componentry as a result of the increased retained heat levels in the toaster. While the problem might be partially improved by lowering the wattage levels of the toaster heating elements, it has been found difficult to lower the wattage levels sufficiently to solve the problem of retained convection heat levels while at the same time maintaining sufficient radiant heat capability to provide a reasonable toasting performance. The problem becomes more serious upon decreasing the body width of the toaster and also when it is desired to maintain a cool touch to the outer walls of the toaster.
Accordingly it is an objective of the present invention to provide a means of permitting the escape of convection heat from a toaster of the type disclosed in the foregoing while still providing a means of preventing escape of flames from the toasting compartment in the unfortunate event of a toaster fire occurring. As a result, the invention also aims at being able to keep heating element wattage levels at a value sufficient to provide good radiant heat performance and thereby good toasting performance.